java - Where is array's length property defined?

Question

We can determine the length of an ArrayList<E> using its public method size(), like

ArrayList<Integer> arr = new ArrayList(10);
int size = arr.size();

Similarly we can determine the length of an Array object using the length property

String[] str = new String[10];
int size =  str.length;

Whereas the size() method of ArrayList is defined inside the ArrayList class, where is this length property of Array defined?

Answer 1

Arrays are special objects in java, they have a simple attribute named length which is final.

There is no "class definition" of an array (you can't find it in any .class file), they're a part of the language itself.

10.7. Array Members

The members of an array type are all of the following:

• The public final field length, which contains the number of components of the array. length may be positive or zero.

• The public method clone, which overrides the method of the same name in class Object and throws no checked exceptions. The return type of the clone method of an array type T[] is T[].

  A clone of a multidimensional array is shallow, which is to say that it creates only a single new array. Subarrays are shared.

• All the members inherited from class Object; the only method of Object that is not inherited is its clone method.

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Resources:

• JLS - Arrays